Tablenator

Tablenator assists developers in making tables accessible. The extension illustrates how a screen reader would interpret each table on the page. The add-on numbers the tables, and shows any issues it finds with the tables. For example, it indicates tables where there have no accessibility markup, or tables where there are conflicting accessibility markups.

The add-on also indicates, with colour, the relationships of tables cells with other cells.

Details about this extension can be found at http://tablenator.com